Your only hope really of reasonably increasing your chances of getting real stuff is to go to a hospital, see a doctor and get it from the hospital pharmacy. Even then it might be a copy. Cost will be about the same as buying what is almost surely a copy from a pharmacy.

However, the Indian generics sold under the table at pharmacies are probably real functional Indian generics and not copies of Indian generics. Although I might be wrong......

If in doubt, you can verify your purchase with the manufacturer. The boxes all come with batch numbers and bar codes. If you email the manufacturer with the info, along with where purchased, most US or EU based manufacturers will reply back. If you do not purchase in a hospital, go to a reputable pharmacy. For example, Boots has quality standards.